Hydrogenation process



Patented June 18, 1946 HYDROGENATION rnocsss some 5. Greensfelder, Oakland, and Walter H.

Peterson, Berkeley, Calif., assignors to Shell Development Company, Sari Francisco, Calif., a

corporation of Delaware Application May 9, 1944,

No Drawing.

Serial No. 534,807

7 Claims. 1

This invention relates to the controlled partial saturation of unsaturated organic compounds ages, especially their conversion to the corresponding mono-olefinic compound.

The hydrogenation of polyolefinic compounds such as dioleflns to the corresponding monooiefinic compound is rendered difficult by the tendency of the reaction to continue beyond the mono-olefin stage with resulting production of undesired completely saturated products. Attempts to eliminate such undesired reaction in the past have not been satisfactory. Thus, for example, it has been proposed to reduce the formotion of parafllns in hydroeeriating polyolefins to mono-olefins by limiting the proportion of hydrogen to the stoichiometric requirement for the production of mono-oiefins or to even lower proportions. However, this leads not only to incomplete hydrogcn'ation of the polyoleflns to mono-oleiins but also favors polymerization and the consequent deposition of higher boiling prodnets on the catalyst greatly reducing its effective life. Furthermore, even with such low hydrogen ratios the formation of saturated products has been by no means completely suppressed.

It is an important object of the present invention to eliminate the foregoing and other defects of previous methods for the partial hydrogenation of organic compounds having at least four unsaturated carbon atoms in a non-aromatic group. Another object is to provide an efficient, economical and commercially practical method for converting polyoiefinic compounds to mono-olefinic compounds with minimum formation of saturated products. A further object is to selectively convert the diolefinic content of hydrocarbon mixtures, such, for example, as the products of thermal or catalytic cracking and the like containing dioleiins and mono-oleflns. to mono-olefins without substantially reducing the total olefin content thereof. Still other objects and advantages of the invention will be apparent from the following description of the new selective hydrogenation process.

In the interest of clarity, the invention will be described with more particular reference to its application to the production of mono-olefins from hydrocarbon mixtures containing diolcfins, particularly conjugated diolefins. and the corresponding mono-olefins because this type of operation presents special difficulties due to the tendency of such diolefins to polymerize and interfere with the desired hydrogenation. However, this application of the process is intended to he illustrative only and it will be understood that the invention is not limited to the treatment of coniugated dioleflns nor with respect to the source or nature of the unsaturated compound treated or of any other components which maybe present therewith and that, by proper adjustment of operating conditions, the invention may be ap plied to the selective hydrogenation of other unsaturated compounds having at least four unsaturated carbon atoms in a non aromaticgroup.

It has now been found, and the invention is based upon the discovery, that the hydrogenation of dioleflns can be carried out so as to produce mono-olefins with minimum formation of com pletely saturated products provided a speciattype of catalyst is used to promote the reactlq ipand excessive reaction times are avoided. variety of catalysts, particularly the various m'e 9.15 of groups 6, 7 and 8 of the periodic system such as tungsten, molybdenum, manganese, iron. nickel, cobalt, etc., their sulfides and oxides and combinations thereof, have been proposed for use in divers hydrogenation processes, especially hy drogenations having as an object the production of saturated organic compounds. It was unexpected, therefore, to find that among these many catalytic agents nickel sulfide is unique in the hydrogenation of polyolefinic compounds and that this catalyst is definitely not the equivalent of other hydrogenation catalysts in thisreaction but is capable of substantially completely converting polyolefinic compounds into mono-olefinic compounds without substantial formation of saturated products. This highly selective hydrogenatlon by the use of nickel sulfide of polyole nnic compounds in preference to, and to the substantial exclusion of, hydrogenation of any mono-oleiinic compounds present, is very likely associated with selective surface adsorption. But whatever the explanation, it has been found that catalysts having an active agent consisting predominantly of nickel sulfide are markedly superior to other catalysts in their selectivity for the hydrogenation of polyolefins.

Nickel sulfide catalysts for use in the invention may be prepared in a variety of different ways and the particular form which will be most advantageous in any given case will depend, among other things, on the particular processing method. Thus, for operations in the vapor phase with a fixed bed of catalyst, which is the preferred procedure for treating lower boiling polyclefinlc compounds or mixtures containing such compounds, the catalyst may be used in the form of relatively coarse aggregates or shapes of, for example, about 2 to 12 mesh. When the hydrogenation is to be carried out with the polyolefinic compound in the liquid phase it is usually more advantageous to use the catalyst in a sufficiently divided condition so that it may be employed as a suspension in the reaction mixture. For reaction by the dust or powdered catalyst methed, for example, in the fluid catalyst system relatively finely divided catalyst is also desirable.

The nickel sulfide may be used alone, or may be employed in admixture with other suitable materials which may or may not have catalytic or other activity under the reaction conditions. Thus, nickel sulfide in the form of pellets or granules or other shapes which may be obtained by extrusion. or molding or other treatment of nickel sulfide with or without binders. stabilizers. activators or other components may be employed. Alternatively the nickel sulfide may be used on supporting material or carriers such as silica. alumina, clays, and the like which may or may not have been previously activated in any suitable manner. One simple, advantageous method of producing very effective catalysts is by reacting ordinary nickel hydrogenation catalysts with hydrogen sulfide. For example. nickel nitrate or nickelous formate may be used to impregnate an alumina or majolica carrier and then decomposed by heating at about 250 C. to 350 C. The resulting nickel oxide is reacted with preheated hydrogen sulfide at about 400' C. until the surface is substantially completely nickel sulfide; about four hours of heating with hydrogen sulfide being usually sumcient. Howevenas previously indicated, other methods of catalyst preparation may be used.

The selective hydrogenation of polyclefinic compounds to mono-olefinic compounds may be carried out at various pressures and temperatures depending, at least in part. on the particular starting material being treated. Although relatively high pressures may be employed, it is generally preferred, particularly for operations carried out in the vapor phase, to use moderate pressures between atmospheric and about 200 pounds per square inch. with such pressures. temperatures of about 100 C. to 400 C., preferably about 100 C. to about 350 C. may be used. The optimum temperature and pressure combination within these preferredranges will depend not only on the activity of the catalyst, which may vary with its method of preparation and with its period of use (fresh or newly regenerated catalysts generally requiring less drastic conditions, that is a lower temperature or a lower pressure or both, than catalysts which have been in use for some time), but also on the other operating conditions. For example, a short time of contact of the reactants with the catalyst may require more intense conditions, than when longer contact times are used. Liquid hourly space velocities of about 0.5 to 12 are generally suitable and in any case the reacted hydrocarbon is most advantageously removed from the reaction zone substantially as fast as one molecule of hydrogen per molecule of diolefln is reacted therewith.

In the present process, the ratio of hydrogen 4 of dioleflns without substantial conversion oi mono-olefins. However, it is preferred to employ a substantial excess or hydrogen over the stoichiometric requirement for th desired hydrogenation, advantageously at least twice and more preferably 5 to 15 times such requirement is used. It has been found that excess hydrogen of this order has a favorable effect in preventing polymcrization and condensation reactions, which otherwise may cause the catalyst to become more rapidly coated with resinous and carbonaceous materials operating to shorten its effective life. However. nickel sulfide catalysts which have thus lost their selectivity or activity may be regenerated by burnin oil the deposit in a stream 01 air at a temperature preferably not substantially above about 400 C. This treatment sometimes causes an excessive loss of sulfur from the catnlyst with resultant loss of selectivity for the desired diolefin hydrogenation. In such cases the selectivity of the catalyst may be restored by retreatmcnt with hydrogen sulfide or other sulfurous gases at about 350 C. to about 400 C. until 5 surface consisting essentially of nickel sulfide is again produced.

It is also advantageous in order to preserve the selectivity of the catalyst during use, to add a small amount of sulfur (for example. as such or preferably as hydrogen sulfide or other suitable compounds of sulfur) which serves to maintoin the sulfur content of the catalyst. A portion or all of the hydrogen sulfide or the like present in the reactor effluent gases may be recycled, if desired, with the \iilreaoted hydrogen.

The following examples further illustrate the principles of the invention and show in more detail one method of carrying it out. They also indicate the advantages, particularly with respect to selectivity, of the new method of partial hydrogenation of polyoleflnlc compounds.

Example I This mixture was fed at a liquid hourly space velocity of unity over various nickel sulfide catalysts prepared in different ways using various temperatures. pressures and hydrogen to diene ratios. The following table shows the operating conditions employed and the results obtained.

Total oleilns 98% at al yst Analysis of product Temper- Mol ratio, ature. C. H

i dlene Oleilns per cent Nickel sulfide on maiolica Nickel sulfide on i-mesh alumina. Nickel sulfide on B-mesh Alorco grade A alumina. Vlckel sulfide on iLmesh Alorco grade A alumina Flulflded nickel on alumina hyd rogenatinn catalyst Fulllded nickel on alumina byd rogenai ion catalyst to the polyolefinic compound or compounds to be hydrogenated may vary within wide limits because of the aforementioned discovery that nickel sulfide catalysts promote selective hydrogenation nickel sulfide catalysts according to the invention.

Example I! A mixture of normal and iso butanes and but-ylencs and 1,3-butadiene containing 53.2% total oleilns. 15.8% isobutylene and 10.9% butarlienc was submitted to selective hydrogenation in the presence of nickel sulfide catalyst, under Example IV Limonene was selectively hydrogenated in the liquid phase using nickel sulfide supported on alumina as the catalyst. At a reaction temperature of 150 C. and a pressure of 1000 p. i. g. the hydrogenation proceeded at a iairly uniiorm rate until one mole of hydrogen per mole of limonene had been consumed after which the the conditions and with the results shown below: consumption of hydrogen ceased. Analysis Analysis or product 'l'crnpcra- Pressure, Foul rail, Moi ratio, tnrc, *0. p.1 i. g. L. ll. 8. V. H; Iodicno Total Tertiary Dlmo olciins, oleilns, per cent per cent 9 17s... mo 0.! ii.8 can u iiiii... an 2.0 M 0.13 193... so 1.3 7.0 us 245.. so 1. o o. o M. o is. 7 3. i8 248... so u. n a. a as. a 14. n n. 02 250. 100 3.4 6.2 54.2 15.0 0.05 252. 100 2.0 6.0 54.7 15.9 0.03 252. 5D 4.1 4.8 ".72 253 Mi 2." 6. ii 54. 6 16. 3 ii. ll

Butadlene is converted almost exclusively to beta- 95 showed that the .product contained only monohutylenes in this process. Tests on the selective hydrogenation oi isoprene and piperylene gave data showing that the hydrogen addition takes place predominantly in the 1,4 positions in these cases also. i

Example I I! A mixture of trlmethylcyclohexadiencs obtained by hydrogenating isophorone and dehydrating the resulting product and composed of approximately 75% of 1,1,3-trimethyloyclohexadiene-3,5 and l,1,3-trimethylcyclohexadiene- 2.4 and of l,l-dimethyl-B-methylenecyclohexane-4, was subjected to selective hydrogenation using a nickel sulfide catalyst prepared by reacting nickel oxide deposited on gamma alumina with hydrogen sulfide at 400 C. for four hours.

The hydrogenation was carried out using a pressure of 135 p. s. i. g.. a liquid hourly space velocity of 0.5 and a molar ratio of hydrogen to hydrocarbon of 7.0 to l. The product obtained from operating at 250 C. had the following properties:

Percent muntutm emu-- of mi Since the bromine number of the feed was 260, these results show that the trimethyl cyciohexadlenes were substantially completely converted to trimethylcyclohexenes under these conditions.

It will be seen that the invention offers many advantages particularly with respect to the sclectlvity of the hydrogenation and the eiilciency of the conversions which may be obtained. The new process is also extremely useful and economical due to the freedom from side reactions and the long periods of operation between catalyst regenerations. which are most desirable industrially. While the treatment of conjugated diolefins has been emphasized in the ioregoinu examples, the process is equally applicable to the production of particular mono-oleilns from shown by the following example:

oleflns and that about was methyl isopropyl cyclohexene.

In a companion run there was evidence that unsupported nickel sulfide was somewhat less active as a catalyst but the hydrogenation was selective in this case also.

Other polyolefinic hydrocarbons which may be similarly converted to the corresponding monooleiins are. for example. the hexadienes. isoprene. piperylene, cyclohexadiene. methyl cyclohexadiene. dipentene. terpinene, etc. Compounds having an acetylenic group and an olefinic group in the molecule such as vinyl acetylene and the like may likewise be used as starting material for the preparation of mono-oleflns according to the invention. The invention is not restricted to the treatment of hydrocarbons alone, but may be applied to the partial saturation oi substitution products thereof having a plurality of aliphatic unsaturated groups in the molecule, such, for example, as polyoleflnic acids. alcohols, esters. others, ketones, aldehydcs. amines. nitro compounds, halides, sulfides. mercaptans. etc. The substituent groups or elements present may be inert under the reaction conditions or may be such as to undergo simultaneous change without interfering with the partial hydrogenation of the unsaturated bonds present. Thus. the invention may be advantageously used to reduce the unsaturatlon of drying oils while avoiding formation of completely saturated products. Sorbic acid may be converted by the new process to the much more stable 3-hexconic acid. Geraniol may be likewise treated to obtain the corresponding decyienol and lsobutenyl isobutyl ketone may be produced from phorone. Butaclienyl acetataior example. is typical of another type or substituted starting material which may be used in the process. Aromatic or heterocyoiic groups or both may also be present in the feed material.

It is thus apparent that the invention is capable oi wide variation not only with respect to the compounds which may be selectively hydrogenated and the reaction conditions which may be used but also in regard to the methods of opcmtion which may be used. Thus. while continuous operation has been emphasized as the preferred procedure. the new process may also be carried out intermittently or batchwise. Where the selective hydrogenation is to be carried out with the material to be hydrogenated in the liquid phase. it is often advantageous to employ solvents or diluents, especially with starting materials of high volatility as the operating pressure may be thereby reduced. Still other variations in the process may be made and it will be evident that the invention is not limited to the details described by Way oi illustration nor by any theory proposed in explanation of the improved results obtained.

We claim as our invention:

1. A process for producing a mono-olefinic compound from the correspondlngdiolefinic compound to the substantial exclusion of the corresponding saturated product of hydrogenation which comprises reacting said dioleiinic compound with hydrogen in the presence of nickel sulfide.

2. A process for substantially completely converting a diolefin to the corresponding mono-olefin without appreciable formation of saturated carbon compounds which comprises reacting said dioiefin with hydrogen in the presence of nickel sulfide.

3. A process for producing a mono-olefin from a diolefin to the substantial exclusion of the corresponding saturated product of hydrogenation which comprises reacting said diolefln with hydrogen in the presence of a nickel sulfide catalyst and removing reacted hydrocarbon from the reaction zone substantially as fast as one molerule of hydrogen per molecule oi. dioiefin is reacted therewith thereby obtaining a mono-olefin substantially devoid of paraiflns.

4. A process for converting a mixture of monoand diolefins predominating in mono-oleflns substantially to mono-olefin which comprises contacting said mixture and a substantial molar excess of hydrogen based on said diolefln'with nickel sulfide under hydrogenating conditions and removing reacted hydrocarbon from the reaction zone after reaction of one molecule of hydrogen per molecule of diolefin thereby to convert said dioleflns to the corresponding mono-oiefins althout appreciable formation oi any saturated com-- pounds. k

5. A process 01 producing 2-biitylenes from butadiene which comprises passing butadiene together with at least five mole of hydrogen per mol of diolefln present over a nickel sulfide catalyst at between about and about 400 C. at a liquid hourly space velocity of about 0.5 to 12 thereby to produce Z-butyienes without appreciable production of butane.

6. A process of producing umyienes from the corresponding pentadienes which comprises contacting said pentadienes and a substantial molar excess 01' hydrogen with a nickel sulfide catalyst at temperatures between about 100 and about 400 C. thereby to produce amyienes without appreciable production of pentanes.

'l. A process for producing a mono-oleflnic compound to the substantial exclusion of its corresponding saturated product of hydrogenation which comprises reacting an unsaturated compound having at least four unsaturated carbon atoms in a non-aromatic group with hydrogen under the catalytic influence of a catalyst having an active surface predominating in nickel sulfide thereby to produce a corresponding mono-oieflnic compound to the substantial exclusion of the corresponding saturated product of hydrogenation.

BERNARD S. GREENSFELDER. WALI'ER H. PETERSON. 

